A comparison of bats and rodents as reservoirs of zoonotic viruses: are bats special?

TLDR

Bats are natural reservoirs of several high‑impact zoonotic viruses. The study quantitatively tests whether bats uniquely host zoonotic viruses compared to rodents. The authors compared bat and rodent species, analyzing viral richness and life‑history traits to assess host‑specific factors. Results show bats harbor more zoonotic viruses per species than rodents, driven by higher sympatry and life‑history traits such as smaller litters, greater longevity, and more litters per year, indicating more frequent interspecific transmission, yet rodents remain a major reservoir due to their larger species pool, underscoring the need for predictive frameworks for emerging viruses.

Abstract

Bats are the natural reservoirs of a number of high-impact viral zoonoses. We present a quantitative analysis to address the hypothesis that bats are unique in their propensity to host zoonotic viruses based on a comparison with rodents, another important host order. We found that bats indeed host more zoonotic viruses per species than rodents, and we identified life-history and ecological factors that promote zoonotic viral richness. More zoonotic viruses are hosted by species whose distributions overlap with a greater number of other species in the same taxonomic order (sympatry). Specifically in bats, there was evidence for increased zoonotic viral richness in species with smaller litters (one young), greater longevity and more litters per year. Furthermore, our results point to a new hypothesis to explain in part why bats host more zoonotic viruses per species: the stronger effect of sympatry in bats and more viruses shared between bat species suggests that interspecific transmission is more prevalent among bats than among rodents. Although bats host more zoonotic viruses per species, the total number of zoonotic viruses identified in bats (61) was lower than in rodents (68), a result of there being approximately twice the number of rodent species as bat species. Therefore, rodents should still be a serious concern as reservoirs of emerging viruses. These findings shed light on disease emergence and perpetuation mechanisms and may help lead to a predictive framework for identifying future emerging infectious virus reservoirs.